Colorless printing fluid



Patented Oct. 6, 1953 I David W'. Steinhardt, Dayton,

The National Cash Register Ohio, assi'gnor to Company, Dayton,

Ohio, a corporation of Maryland No Drawing. Application October 20, 195 1,v Serial No. 252,421

1' Claim.

This invention relates to a printing fluid comprising a fluid vehicle containing two color-reactant compounds forming a substantially colorless solution which will produce a mark of one distinctive color hue on record material sensitized with a material which turns one ofthe fluid-held reactant compounds to its colored form on contact therewith, and which will produce a mark of another distinctive color hue on record material sensitized with another material which turns both of the fluid-held reactant compounds to their colored form on contact therewith. The two colors formed when both of the printing fluid-held color-reactants are turned to their colored formblendto producea composite color distinctive from that color hue which is distinctive of the colored form of either reactant.

This fluid is adapted to be usedeither with different pieces of print-receiving or writing.- receiving record material, each distinctively, sen-v sitized, or to a single pieceof print-receiving or writing-receiving record material sensitized in one or more areas with one of the. record material sensitizers and sensitized inone. or more other areas with the other record material sensitizer.

The printing fluid is well adapted for use. in preparing account forms requiring columns of debit and credit entries, and the columns can be. individually sensitized with one or the other of the two record-material sensitizers, producing records of one color, in one columnand records of another color in the other column, using but the single printing fluid, th e color produced being determined by the area to which the printing fluidis applied.

The printing fluid is. adapted for use with any of the common printing fluid applicators such as printing type members, type 7 ribbons, pens, or brushes. The printing fluid containing thetwo reactants can also be. used in making record material having a transfer coating of'wax orhydrophilic cdlloi-d films containing droplets or inclusions of printing fluid, such record material being substantially colorless insofar as the transfer film itself is concerned. Reference ismade to United States Letters Patent No. 2, 54.8,'366, which issued onthe application oi Barrett K. Green and-Robert W. Sandberg, for the type of transfer coating which is composed of a hydrophilic colloid film containing droplets of printing fluid. Reference is made to the application of Chester Davis and Ned Thacker, Serial No. 234,161, filed June 28, 1951, for record material having a transfer coating comprising a wax vehicle in which is incorporated a colorless oily printing fluid of the type describedin this disclosure except that such fluid contained only oneadsorption color reactant producing a single color hue;

As the invention is later described, it will be apparent that on unsensitized'paper record material neither of the color-reactants assume the colored form, and that on paper sensitized with one of the record material sensitizersthe fluid will make the color of theassociated one of the color-reactants in the-reacted form whereas on paper sensitized with the-other color-reactant'the printing fluid will make the composite color, that is to say-the color' produced by blending the colors of both color-reactants in the colored form.

The colorless color-reaetantsdeemed preferable are those aromatic organicgcompounds having a double bond structurewhich is converted to a more highly polarized conjugatedform when adsorbed on acid-like inorganic solid material; such as attapulgite and calciumtsilicates, accompanied by the appearance of color.

Therefore, it' is an object of-this-invention to provide a substantially colorlessv printing" fluid which is adapted for use on sensitized recordmaterial of two kinds, the. printing fluidmaking-a mark of one distinctivehueon paper sensitized with one sensitizing material andmaking a' mark of another distinctive hue on paper sensitized with another sensitizing material.

Another object'of theinvention is to provideaprinting fluid .in which the color-reactants assume their colored-form. by adsorption contact with fine particles ofJinorganic solid material with which the record material issensitized, such inorganic material ha ii fiacid-like properties and hence, acting as an electronracceptor with respect to the printing fluid-held reactant-with which it is associated, changing'it from the colorless form to a colored form.

With these and incidental objects :inview-the invention includes. certain novel features and combinations of ingredients, a preferred-form'or embodiment of which is hereinafter described.

The colors producedbythe printingfluid of this disclosure are immediately produced and are stableto ordinary; environmental conditions;

In .the instance .of Beach of the printingfiuid held'color-forming reactants whichwil'l be disclosed the reaction is of the so-called adsorption type in which an inorganic material with which the paper is sensitized causes a color change in the fluid-held organic reactant when in adsorption contact therewith, without the presence of an ionizing medium being required. Of the color-reactant materials used in the printing fluid are electron donor aromatic compounds having a double bond system which is convertible to a more highly polarized conjugated form upon taking part in an electron acceptor-donor solid surface chemical reaction, giving such reactant its distinctive color hue, and the inorganic paper sensitizing material is one that is an acid relative to the organic reactant with which it is associated, so as to be an electron acceptor when in adsorption contact therewith.

The two fluid-held color-reactants are chosen so that one requires a record material sensitizer of stronger acid characteristics than the other to cause it to change to the colored form. The record material sensitizers are chosen accordingly for their acid strength. Whereas the inorganic material with which one piece of record material or one area of record material is sensitized may act as an electron acceptor for both organic color-reactants held by the fluid, the inorganic material with which the other piece of record material or other area of the same sheet is sensitized, acts as an electron-acceptor only toward one of the organic reactants in the printing fiuid. It is for this reason that the two different colors of printing can be obtained with the same printing fluid.

The preferred printing fluid has a non-evaporating vehicle consisting of chlorinated diphenyl having a chlorine content of about 48%. This vehicle acts as a solvent for the preferred organic color reactants which are dissolved therein in small quantities, as the color intensity produced by these organic reactants in the colored form is of high order. Amounts of the color reactants in the fluid may vary from 1% to 4%, by weight, of each, although 1% of each is sulficient to produce strong color. The color reactant preferred for color reaction on both type of sensitized record material is malachite green lactone which is 3,3 bis(p-dimethylaminophenyl)phthalide, which changes from its normal colorless form to a blue-green on adsorption contact with the inorganic material with which the papers are sensitized. This material normally is a colorless crystalline solid, but it may be dissolved in the specified fluid vehicle. The other organic reactant held by the fluid, and selected for its reaction only with a stronger acidlike inorganic compound may be N-p-nltrophenyl rhodamine B lactam, which is xanthene- 9, o-benzoic acid, 3,6-bis-diethylamino-9-pnitroanilinolactam. This compound, also normally a colorless crystalline solid, is dissolved in the fluid vehicle and produces on adsorption contact with the one record material sensitizing inorganic substance a red color, which combines with the blue-green color produced by the malachite-green lactone to form a purplish lavender color. Thus, it will be understood that the two colors produced by the printing fluid are distinctive in hue, one being in the bluegreen region of the spectrum and the other being in the purple-lavender region of the spectrum. The preferred record material sensitizing ingredient for causing the appearance of color in both of the reactant compounds is attapulgus clay which may be applied to the paper by coat- 4 ing processes normal to the paper coating in dustry in which the clay is adhered to the paper by adhesives, such as paper-coating starch and synthetic latex materials.

The attapulgus clay may also be incorporated with paper pulp before it enters the paper-making machine and, thus the paper so made from it will be sensitized through and through, so both sides will produce color when the printing fluid is applied thereto. Other methods of coating the paper are by rolling the coating on one or both sides, or by spraying the material on at the wet end of the sheet on a paper mill. The inorganic recordmaterial sensitizing agent which causes the formation of color in only one of the organic color-reactants held by the fluid is calcium silicate material made by reaction between a water-soluble calcium salt and sodium silicate, such as described in my co-pending application for United States Letters Patent Serial No. 252,420, filed on the same day this application was filed. This will not cause the lactam compound specified to change to the colored form, but will cause the malachite-green lactone to change to the colored form.

The fluid vehicle may be an evaporable vehicle, if desired, aromatic solvent such as toluene being used in the same proportions, as the chlorinated diphenyl.

The preferred color-reactants are not to be deemed the only ones useful. For instance, 3,3 bis (p-ethylarninophenyl)phthalide, producing, a light blue color, may be used in place of malachite green lactone.

While the form of the invention herein described is admirably adapted to fulfill the objects primarily stated, it is to be understood that it is not intended to confine the invention to the one form or embodiment herein disclosed, for it i susceptible of embodiment in various other forms.

What is claimed is:

A substantially colorless printing fluid which will make marks of one color on record sheet sensitized with attapulgite and marks of another color on record material sensitized with calcium silicate, said fluid consisting of an oily chlorinated diphenyl in which have been dissolved xanthene-Q, o-benzoic acid, 3,6-bis-diethylamin0- Q-p-nitroanilino-lactarn and a compound selected from the group consisting of 3,3 bis(p-dimethylaminophenyhphthalide and 3,3 bis(p-diethylaminophenyl) phthalide.

DAVID W. STEINHARDT.

References Cited in the file of this patent UNITED STATES PATENTS Number Name Date 1,514,222 Murray Nov. 4, 1924 1,553,556 Rogers Sept. 15, 1925 2,068,204 Smith Jan. 19, 1937 2,137,463 Shields Nov. 22, 1938 2,474,084 Adams June 21, 1949 FOREIGN PATENTS Number Country Date 5 713,025 France Oct. 17, 1931 I 

